In brief
- A changeover claim is only evidence when someone shows the wiring diagram, the interlock and a witnessed transfer test.
- Without a mechanical or electrical interlock, a generator can backfeed the mains and put anyone touching the line at risk.
- Walk a recent site the team wired and ask the building owner what happened at the first power cut.
Contents
A generator changeover in Borama can be checked before you award the work: ask for the changeover drawing, the interlock arrangement, the cable and breaker sizes, and a witnessed transfer test. A changeover claim is unverified when nothing is documented and nothing is tested. Attendance on a site does not prove the electrician can isolate the mains, start the set and transfer load without a backfeed.
What does a changeover claim look like without evidence?
A claim without evidence is usually a verbal promise, a list of past jobs, or a photocopy of a certificate with no name or date on it.
Competency shows up in documents and in behaviour. Ask for the single line diagram of the changeover, the rating of the changeover switch or contactor, the size and route of the cable between the generator and the panel, and the earth connection at both ends. Ask who will sign the test sheet and what instruments they will use. Ask to see the insulation resistance and continuity results for the final circuits that the generator will feed.
If the person cannot produce a drawing for a job of this size, treat the claim as unverified. A changeover is not a socket. It sits between two supplies, and the person wiring it must understand the difference between the neutral and the earth, and what happens when the mains returns while the generator is still running. Confirm the required arrangement with the project engineer and the utility before work starts.
How does an unverified changeover become unsafe power transfer?
Unsafe power transfer starts when the two supplies can connect at the same time, and the risk sits with whoever touches the line next.
A generator feeding a building with no interlock can push current back up the service cable. That is a backfeed. It can energise a line that a utility worker believes is dead, and it can damage the generator when the mains returns out of phase. A mechanical interlock, a keyed switch or an electrically interlocked contactor keeps both supplies apart. Only one source can be closed at a time.
Other failures follow the same gap. A changeover with no neutral switching can leave the earth path carrying current. A set with no earth electrode at the generator frame can hold a fault voltage on the metalwork. Cables sized by guesswork can heat under load. None of this appears on a handover day when the power is on and the lights work. It shows up at the next cut, or at the next inspection. Ask the municipal engineer's office what it requires for a generator connection, and put the answer in the contract.
How do you test the work before you pay?
You test the work by watching the transfer happen, and by reading the records afterwards.
Arrange a witnessed test. With the load off, start the generator, close the changeover, and check that the mains side is dead. Then simulate the mains return and watch the transfer back. Check the neutral and earth links, the breaker ratings against the cable, and the generator earth. Record the readings and the date.
- Ask for the changeover drawing and a schedule of the breakers and cables.
- Ask for test records from a recent job, with the instrument used and the person who signed.
- Walk one completed site and ask the owner what happened at the first power cut.
- Agree in writing who commissions the changeover and who signs it off.
What to do next
Before you release the next payment for electrical work in Borama, ask the contractor for the changeover drawing, the interlock detail and a signed transfer test record. If any of the three is missing, hold the item on a snag list and ask the project engineer to witness the test. Check what your contract allows before you change any payment terms.
Frequently asked questions
Can I accept a verbal assurance that the electrician has done changeovers before?
No. Ask for the drawing, the interlock arrangement and one signed test record from a completed job. Then watch a transfer test on your own site before you accept the work.
What is the single biggest danger in a generator changeover?
A backfeed. If both supplies can close at once, the generator can energise the mains line and put anyone working on it at risk. A mechanical or electrical interlock prevents that.
Who signs off a changeover in Borama?
Ask whoever holds the relevant local authority role what documentation they require, then name the person who will witness and sign the transfer test in the contract.
Local reporting: this article is written for building work in Borama and Somaliland. Ground conditions, prices and rules differ between places; confirm the details for your own site.